1. Field of the Invention
The invention is concerned with stabilized fuels and lubricants. More particularly, it relates to fuel and lubricant compositions to which have been added a complex formed from (1) the reaction product of an alkylsuccinic anhydride and a polyhydroxy compound and (2) a metal salt.
2. Discussion of the Prior Art
A great deal of effort has been directed to providing a lubricant which will permit present-day automotive engines to be operated at a high level of efficiency over long periods of time. A difficulty arises because lubricating oils tend to deteriorate under the conditions of use, with attendant formation of sludge, lacquer and resinous materials which adhere to the engine parts, thereby lowering the operating efficiency of the engine. To counteract the formation of these deposits, certain chemical additives have been found which, when added to lubricating oils, have the ability to keep the deposit-forming materials suspended in the oil, so that the engine is kept clean and in efficient operating condition for extended periods of time. These added agents are known in the art as detergents or dispersants.
Metallo-organic compounds are particularly useful as additives in this respect. However, the troublesome deposits which form on the skirt of the piston and on the walls of the combustion chamber, as well as on valves and spark plugs are also partially attributable to these metal-containing additives employed in the lubricant. Whenever oil is burned in the engine, as occurs with the oil film present on the cylinder wall during the combustion stroke, many metal-containing additives present in the oil may form an ash which is partially deposited on the various surfaces of the combustion chamber and on those of the spark plugs and valves.
Several known non-metallic detergents have previously been used in lubricating compounds. However, they have not proved to be entirely satisfactory. Additives which are particularly effective are based upon condensation of products of a hydroxyaromatic compound, an aldehyde and an amine, the so-called Mannich reaction. These additives are multi-functional improvers especially adapted for mineral oils and as pour point depressants therein. These compounds have also been recognized as exhibiting detergent properties. A preference has existed for the use of hydroxyaromatics which are unsubstituted, particularly phenol and alpha and beta naphthols.
U.S. Pat. No. 3,808,131 discloses a metal coordinated complex, useful as a detergent in lube oils and fuels, made by reacting an amine-acid product with an alkylsuccinic anhydride or acid and a metal salt. U.S. Pat. No. 3,755,167 describes a lube or fuel additive prepared by reacting an amine-aldehyde product with an alkylsuccinic acid or anhydride and a metal salt. This additive is also useful as a detergent. U.S. Pat. No. 3,632,510 discloses salt formation with materials similar to those used in the present invention.